#include <stdio.h>
int main(void){
	printf("plz enter the upper bound:\n");
	int n;
	double i,sum;
	scanf("%d",&n);
	sum=0;
	for(i=1.0;i<=n;i++){
		sum = sum+(2*i-1)/(i*(i+1));
	}
	printf("SUM=%.2lf",sum);
	return 0;
} 
